Carboxy phosphates



:simple esters such as n-propyl, di-n-butyl, v 'di-tert-amyl,di-n-hexyl, di-n-heptyl, di-n-octyl or bis(2- butyl phosphate,

2,980,722 v CARBOXY PHOSPHATES Gail H. Birum and James L. Dever, Dayton,Ohio, assignors to Monsanto Chemical Company, St. Louis,

Mo., a corporation of Delaware 7 v No Drawing- Filed May 8, '1959, Ser.No. 811,791 6 Claims. (Cl. 260-461) i According to the invention dialkyll-carboalkoxyalkyl phosphates are prepared by heating a dialkylphosphonate with an alkyl 2-oxoalkanoate substantially according to inwhich alk denotes anallgyl I a carbon atoms and Ris an alkyl radical offrom 1 to 4 carbon atoms.

Presently useful dialkyl phosphonates' are, e.g., the

dimethyl; diethyl, diisopropyl, didi-tert-butyl, diisobutyl, di-n-amyl,

,ethylhexyl) phosphonateand the mixed esters such as ethyl methyl,n-butyl isopropyl, Z-ethylhexyl n-propyl,

ethyl n-hexyl, tert-amyl n-octyl, isobutyl methyl, or ethyl n-heptylphosphonate.

The presently useful alkyl 2-oxoalkanoates are the alkyl esters ofpyruvic; ZI-dxobutyric, 2-oxovaleric "or2-oxohexanoic acid, e.g.,methyl'pyruvate, n-propyl pyruvate, n-butyl' pyruvate, 2-ethylhexylpyruvate, 7 butyrate, isopropyl 2-oxobutyrate, n -octyl 2-oxobutyrate,

methyl 2-oxovalerate, n-butyl 2-oxovalerate, n-octyl 2- ':oxo-valerate,ethyl. 'Z-oxohexanoate, tert-butyl 2-oxo- '1 i Dialkyl.1-carboalkdxyalkyl phosphates provided by the which ispreparedfromdimethyl phosphonate and ethyl -pyruvate,"di-n-butyll-carbo-n-propoxybutyl phosphate which is prepared fromdi-n-butyliphosphonate and nradical of from 1 to 8 5' :to the'scheme 5invention are, e.g., dimethyl l-carboethoxyethyl phosphate propyl2-oxovalerate, bis(Z-ethylhexyl) l-carbo-n-butoxy-r propyl phosphatewhich is prepared from bis(2-ethyl-" hexyl) phosphonate and n-'butyl2-oxobutyrate, and diethyl l-carbomethoxyamyl phosphate whichis-prepared lfro'rn" diethyl phosphonate and methyl 2-oxohexanoate.

Other presently provided carboxylated phosphatesiarfi, e.g., dimethyll-carbomethoxyethyl phosphate, diethyl l-carbon-butoxyethyl phosphate,di-n-propyl l-carbomethoxyethyl phosphate, di-n-butyll-carbo-n-octyloxyethyl phosphate, di-n-amyl l-carboisopropoxyethylphosphate, bis(2- ethylhexyl) l-carbomethoxypropyl phosphate,di-tertamyl l-carbo-n-butoxypropyl phosphate, diethyll-carboethoxypropyl phosphate, dimethyl l-carbo-n-propoxydiethyll-carboethoxybutyl phosphate, di-n-hexyl l-carbo-n-hexyloxybutylphosphate, diethyl lcarboethoxyamyl phosphate, di-n-butyll-carbo-n-butoxyamyl phosphate, and di-n-octyl l-carbo-npropoxyamylphosphate.

Preparation of the present dialkyl l-carboalkoxyalkyl phosphates iseffected by heating the dialkyl phosphonate with thealkyl-Z-oxoalkanoate at a temperature of over 100 C. and less than 200C. Since the reaction probiological toxican a l 2 coeds by addition ofone mole of said phosphonate with one mole of said 2-oxoalkanoate, thesereactants are advantageously employed in such stoichiometric proportion.I-Iowever, since either the unreacted oxo-ester or the unreactedphosphorus ester may readily be recovered from the final reactionproduct, an excess of either the 0x0- I ester or of the dibasicphosphonate may be used. Such an excess may conveniently serve asdiluent; however, no jdiluent need be employed. The reaction may also beefiected in the presence of extraneous diluents or solvents. As' will beappreciated by those skilled in the art, such diluents orsolvents'should have a boiling point which will permit operation at atemperature of over C. Examples of presently useful liquids are, e.g.,xylene, toluene, tetraliri, etc. Use of higher temperatures, i.e.,temperatures of, say, C; generally serves to reduce the reaction time;hence,.when a diluent is used it should advantageously have a boilingpoint and be employed in such a quantity that operation within 130 C. to190 C. 'is permitted. Progress of the reaction is readily followed bynoting cessation in change of viscosity, refractive index, etc; When nodiluent is used and the reactants are present in the equimolarproportion, the

product is the substantially pure dialkyl' l-carboalkoxyalkyl phosphate.When the reaction has been conducted in the presence of an inert solventand/ or an excess of'one of the reactants, distillation of the reactionmixture is generally employed to give the substantially'pure carboxyphosphate. For many purposes, however, a crude reaction mixturecomprising said phosphate in thereaction diluent may be used directly,e.g., as gasoline additive or i The present dialkyl l-carboalkoxyalkylphosphates are also obtainable by contacting a dialkylphosphorohalidatewith an alkyl 2-hydroxyalkanoate substantially according in which alkdenotes an alkyl radical of from no 8 carbon atoms, R is an alkylradical of from 1 to 4 carbon atoms and X is halogen. Examples ofpresently useful phosphorohalidates are dimethyl, diethyl, dipropyl,dibutyl,- diamyl, dihexyl, bis(2 -ethylhexyl), di-n-o'ctyl,"ethylmethyl, amyl .butyl or hexyl propylphosphorochloridate,.phosphoroiodate or phosphorobromidate. The

or 2-hydroxyhexanoate. 1 1 a Reaction of'the dialkyl phosphoroh'alidatewith" the hydroxyalkanoate may be conducted at ordinary or increasedtemperature in the presence of a basic agent. It is advantageouslyeffected by heating the two reactants at a temperature of from, say, 50C. to C. in the presence of basic agent. The latter serves as scavengerfor the hydrogen halide which is evolved as by-product. Useful basicagents are, e.g., the alkali metal carbonates, the heterocyclic nitrogenbases, tertiary amines. Extraneous, inert diluents or solvents, e.g.,ether, benzene, or xylene, may or may not be employed. Isolation of thedialkyl l-carboalkoxyalkyl phosphate from the crude reaction mixture isreadily efiected by customary isolating procedures, e.g., bydistillation, solvent extraction, etc.

The presently provided carboxy phosphates are stable, well characterizedcompounds which are advantageously employed for a variety of commercialand agricultural purposes. They may be used as biological toxicants,e.g., as insecticides, fungicides, nematocides and bacteriostats; ashydrocarbon oil lubricants and as gasoline additives; as functionalfluids, e.g., in forceflransmissionand dielectric applications; asplasticizers for synthetic resins and plastics, particularly polyvinylchloride; and as flame-proofing agents forcellulosic and carbonaceouscombustible materials in general, -e.g., textile fibers, surfacecoatings,lacquers, polymers, resins and adhesives. The presentlyprovided carboxy phosphates are especially of interest for use aspreignition additives to, leaded fuels. Improved fuels for sparkignition internal combustion engines are obtained by adding the CaIhOXYPhosphate to gasoline containing an organo lead antiknock, e.g.,tetraethyllead. The .quantity of said phosphate thus employed will varyfrom, say, 0.05 to 10.0 moles of the carboxy phosphate per atom of leadpresent in the fuel.

The present invention is to, the following examples:

. Example 1 Ethyl pyruvate, 58.1 g. (0.5 mole) and169.1 g. (0.5 mole) ofdiethylphosphonate were charged into a flask equipped with a stirrer,thermometer, and condenser. This solution was heated at 155-19,0 C. forthree hours. Distillation gave asmall amount of forerun and 90.4;g. (71%yield) of l-earboethoxyethyl .diethyl phosphate,

BJP; 86 C. (0.05 mm), 11 1.4180, and analyzingas Substitution of methyl2-oxobutyrate for the ethyl pyruvate in the above experiment gives agoodyield of diethyl l-carbomethoxypropyl phosphate; and use of bis-(Z-ethylhexyl) phosphona'te instead of the diethyl phosphonate withn-propyl pyruvate gives -bis(2-ety1hexyl) 1- carbo-nvpropoxyethylphosphate.

Example 2 This ,example shows the preparation of the presently P v de-ca hqethoxy diethyl,,p q phates from ethyl lactate and diethylphosphorochloridate.

Ethyl lactate, 34.0 g.. (0.33 mole), and 5.2.2 g. .33

o of die h p p h p ida e( o the w 2 s- (0.33 mole) of pyridine in 200ml.of anhydrous diethyl ether, were charged into a flask equipped withastirrer, thermometer, and condenser.

This fmixture was a then heated at reflux for nine hours. ,Afterfiltration and removal of the solvent, distillation gave .a small amount(47% yield) of 1 -carboethoxyethyl of forerun and 34.4 g.

illustrated by, but not {limited diethyl phosphate, an. 86 o./o.bs mm.,1.4178, and analyzing as follows:

Found Caled. for

CgHmOgP Percent O 42. 36 42. 58 Percent H 7. 52 7. 63 Percent P ,12. 0712.18

Similar reaction of di-n-butyl phosphorobrornidate with methyl2-hydroxybutyrate gives di-n-butyl l-carbomethoxypropyl phosphate.

What we claim is:-

1. A carboxy phosphate of the formula wherein alk denotes an ally1.radica1 of1 to 8- carbon atoms and r R is an; alkyl radicalpf l to 4carbon atoms which comprises heating, at a ternperature of over Cy andbelow 200 -C., =a diallsyl phosphonate having f-rom l to 8 carbonatomsin each radicalwith an-alkyl 2-.oxoalkanoate of the "formula u n r3 T-QT' nQi wherein .:R and alk .are as .hereimdefined.

..5'."T h,e method of ethyl phosphatethaving if-IOIII 1 ate; 8....carbonatoms in each .;alky1 radical and 1 to *8 carbon atoms in zthesalkoxy"radical s which icomprises :heating at. a temperature of over i 100 1C.and Zbelow 200 .C..,. axlialkyl .phosphonatehaving from 1 to8:.carhonatoms .inleach .=a1kyl radical, withan .alkyl. pyruvatehavingzdrom 1 tog-.8 .carbontatoms Pin the ,alkyllradical. l

n6. ilihe -methnd .of preparing .diethyl zl carboethoxyethyl phosphate,which compares heating diethyl 5111105- phonate r withaethyl.pylrpvate. atta temperature of over- 1.00" Csjfltld-JJQIOWZOOyC.

Refer nces Cit junki file i thi eaten:

Kosolapofi: Organo gPhosphorusCompounds (1950), iohn Wiley & Sons, New"York; N.1'Y.,pages 123424. (Copy inRQ-ScientificLibraryJ 1 preparingua.diallgyl vl-carboalkoxy-

1. A CARBOXY PHOSPHATE OF THE FORMULA
 4. THE METHOD OF PREPARING ACARBBOXY PHOSPHATE OF THE FORMULA